1. Field of the Invention
The present invention relates to a method and apparatus for absorbing energy when a body part of an occupant of a vehicle contacts an interior part of the vehicle, thereby reducing the trauma caused by the impact. More particularly, one embodiment of the present invention relates to an impact absorbing member that may be disposed between a trim member and a vehicle seat structural member to create a crash pad for rear seat occupants on the rearwardly facing surface of a vehicle seat.
2. Background Art
Automobile interiors are designed to incorporate both active and passive occupant protection systems. An example of an active occupant protection system is the well known inflatable air bag that is deployed upon impact. Passive impact absorbing systems include foam padding, ribs on plastic trim parts, aluminum honeycomb pads, and the like. One example of a static system is energy absorbing elements incorporated into a headliner. Vehicle headliners line the inner surface of a vehicle roof and may include foam padding, aluminum honeycomb structures, paper, foil and plastic pre-forms. One product known as xe2x80x9cO-Flexxe2x80x9d that is sold by a company of the same name comprises a wound paper/foil member formed in a generally square tube configuration.
The cost of engineering and manufacturing a wide variety of impact absorbing products adds to the total cost of the vehicle. The use of a plethora of different impact absorption products complicates computer-aided design and computer simulation for optimization of impact absorption systems. Energy absorbing countermeasures must be designed to provide specified levels of impact protection within certain space limitation parameters. Availability of a myriad of different impact countermeasure products increases the cost of engineering due to the difficulty of matching products to applications. Further, many impact energy absorbing countermeasure products are relatively high-cost components.
With prior art impact absorbing products, design flexibility is limited in many instances and optimum performance for various impact mechanics systems of various vehicles is difficult to achieve.
Aluminum honeycomb energy absorbing parts or O-Flex type products are complex sub-assemblies. Such products may be made of aluminum honeycomb material or exotic combinations of materials to meet exacting impact absorption standards within limited spaces defined between decorative trim members and structural body parts.
The use of aluminum, cardboard, plastic, and other materials also results in additional cost due to the need to meet performance standards within design parameter temperature specifications. Different types of plastics, foams, and composite materials all have different temperature characteristic profiles that require rigorous product testing to assure compliance with impact standards and constant performance at all foreseeable temperatures.
There is a need for an impact absorption product that offers maximum design flexibility and ensures optimum impact absorbing performance in a variety of vehicles. There is also a need for a low cost impact energy absorbing countermeasure product that may be manufactured using efficient metal stamping processes. There is also a need for an all metal impact countermeasure product that is unaffected by temperature and is less dependent on rate of strain, thus lending itself to simplified computer simulation and optimization of designs. There is also a need for impact countermeasure products that may be used in headliners, roof support pillars, doors, dashboards, sunroof frames, and the like.
Vehicle seats are subject to designs standards for collision energy absorption. Vehicle seats such as that shown in FIG. 25 of the attached drawings have been designed to include expanded polypropylene foam blocks A in the corners of the seat back shell B between the seat back shell B and the structural frame C of the seat. Expanded polypropylene foam has been found to be relatively inefficient at absorbing energy. Energy absorption is measured by determining the level of deceleration over the time period over which an impact condition occurs. The level of deceleration must be less than a threshold value if the impact duration lasts more than a predetermined time interval.
Some disadvantages relating expanded polypropylene foam energy absorbing members include the cost of these and other engineered foam products. Other disadvantages associated with expanded polypropylene foam include the difficulty of assuring precise control of energy absorption efficiency. Further, expanded polypropylene foams tend to be subject to variability in the manufacturing process. Variations in blowing agent activity, humidity and temperature may affect the impact absorption characteristics of manufactured engineered foam products.
These and other needs and problems associated with prior art products are addressed by the present invention as summarized below.
According to one aspect of the present invention, a vehicle interior is provided with an impact absorbing assembly. The impact absorbing member is attached to a trim component with the vehicle interior. The impact absorbing member may comprise a sheet form body portion and a plurality of tabs extending from the body portion. The tabs are partially separated from the body portion and a bendable hinge connection is provided along at least one edge of each tab where the tabs are still attached to the body portion but are bent so that the tab extends from the body portion. A covering layer is applied to the body portion on the side facing away from the structural component.
According to another aspect of the invention, an impact absorbing assembly is provided on an existing structural component of a vehicle interior. The structural component of the vehicle interior functions as an impact absorbing member having a body portion and a plurality of tabs extending from the body portion. The tabs are partially separated from the body portion with a bendable hinge connection being provided along at least one edge of each tab. A covering layer is applied to the structural component to cover the tabs for aesthetic purposes.
According to another aspect of the invention, a method of making an impact absorbing assembly for a vehicle is provided. The method includes the step of providing a sheet metal member and partially severing at least one tab from the sheet metal member. The tab is bent to extend outwardly from one side of the sheet metal member to thereby form a bendable hinge connection between the body portion and the portions of the tab that are not severed from the body portion where the tab is bent outwardly from the body portion.
According to another aspect of the method of the present invention, a method is disclosed for absorbing impact forces that are applied when an occupant of a vehicle hits a structural component of a vehicle interior. The method includes providing on a structural component an impact absorbing member having a sheet form body portion and a plurality of tabs extending from the body portion. The tabs are partially separated from the body portion with a bendable hinge connection being provided along at least one edge of each tab. When a force is applied to the occupant of the vehicle, it may cause the occupant to contact the impact absorbing member with an amount of force greater than a threshold value. When the occupant contacts the impact absorbing member with a force grater than the threshold value, the tabs are plastically deformed thereby absorbing a part of the force applied to the impact absorbing member by the occupant.
According to other aspects of the invention, the tabs may extend either toward or away from the structural component. The tabs may be arranged in rows or columns. The tabs may be contoured, either individually or relative to adjacent tabs. The impact absorption characteristics of the assemblies may be modified by changing the height of the tabs, thickness of the material, spacing of the tabs, angle of the tab relative to the body portion and arrangement of the tabs on the body portion. The impact absorption characteristics of the assembly may also be modified by changing the geometric configuration of the tabs. The tabs may be flat tabs or may include stiffening ribs, a plurality of planar walls, or curved walls. The tabs may be arranged in groups in a circular pattern around an opening or may be formed to include two or more bendable hinge connections to the body portion. The tabs may also be formed in a partially circular shape or may be formed with a central wall having two sidewalls connecting the central wall to the body portion. The tabs may be formed to extend from one or both sides of the body portion of the sheet and may be formed in a wide variety of geometric shapes including an L-shaped configuration, or the like.
According to another aspect of the invention, the body portion of the impact absorbing member may be formed as a flat or curved member. The body portion may also include one or more stiffening ribs. Further, the body portion may include surface features such as holes or metal stake fasteners formed around a pierced hole that provide jagged edges that facilitate securing the impact absorbing member to a structural member or the covering layer.
According to another aspect of the invention, the structural member may be a roof support pillar, dashboard, roof edge, or other interior part that is covered by a molded plastic trim piece. The impact absorbing member may be attached to the trim piece prior to the trim piece being attached to the structural member. Further, the impact absorbing member may have a curved central wall and at least one sidewall that conform to an inner surface of the plastic trim piece.
According to still another aspect of the invention, the body portion of the impact absorbing member may have at least one clip provided thereon for attaching a wiring harness to the impact absorbing member.
According to yet another aspect of the invention, design flexibility is maximized to permit optimization of impact absorbing assemblies in a wide range of vehicles. The impact absorption characteristics of the assembly may be modified by changing the size, shape, and placement of the tabs.
According to a further aspect of the invention, the impact absorbing member is preferably formed of steel or aluminum and may be formed by standard stamping processes. Since the impact absorbing member is formed of metal, the stress-strain properties are less dependent on the rate of strain which permits simpler computer simulation for part design and verification of impact absorption characteristics. Metal construction also ensures consistent performance in a wide range of temperatures.
According to another aspect of the present invention, a vehicle seat is provided with an impact absorbing assembly. The impact absorbing assembly is attached to the seat back shell between a portion of the seat back shell and a structural component of the vehicle seat. The impact absorbing member is a metal member that is designed in the form of a bendable hollow structure that may be bent where an adjacent walls intersect or in the form of tabs that may be bent at a bendable hinge.
According to the method of the invention, an impact absorbing assembly is provided as part of a vehicle seat by initially forming a sheet metal member by conventional sheet metal roll forming or sheet metal fabricating processing techniques. After forming, the metal impact absorbing member is assembled to the vehicle seat back between the vehicle seat back and a structural portion of the seat back. A plurality of metal impact absorbing members may be provided about the periphery of the vehicle seat back or at an interior location thereof. The seat back shell is assembled to the vehicle seat with a metal impact absorbing member being oriented to bend in the event the rearwardly facing surface of the vehicle seat is impacted during a collision.
According to one embodiment of the present invention the metal impact absorbing members include a metallic body having a plurality of tabs cut from the body that are bent at a bendable hinge to an approximately perpendicular orientation relative to the metal body.
These and other features and advantages of the present invention will be better understood by one of ordinary skill in the art in view of the attached drawings and in light of the following detailed description of several modes of practicing the invention.